Catalytic Activity of Horseradish Peroxidase Immobilized on Pristine and Two‐Photon Oxidized Graphene

Abstract Biosensors based on graphene and bio‐graphene interfaces have gained momentum in recent years due to graphene's outstanding electronic and mechanical properties. By introducing the patterning of a single‐layer graphene surface by two‐photon oxidation (2PO), the surface hydrophobicity/hydrophilicity and doping can be varied at the nanoscale while preserving the carbon network, thus opening possibilities to design new devices. In this study, the effect of 2PO on the catalytic activity of the noncovalently immobilized enzyme horseradish peroxidase (HRP) on single‐layer graphene‐coated Si/SiO2 chips is presented. To monitor the activity continuously, a simple well‐plate setup is introduced. Upon controllable 1–2‐layer immobilization, the catalytic activity decreases to a maximum value of 7.5% of the free enzyme. Interestingly, the activity decreases with increasing 2PO area on the samples. Hence, the HRP catalytic activity on the graphene surface is locally controlled. This approach can enable the development of graphene‐bio interfaces with locally varying enzyme activity

Area‐Selective Atomic Layer Deposition on Functionalized Graphene Prepared by Reversible Laser Oxidation

Area-selective atomic layer deposition (ALD) is a promising “bottom-up” alternative to current nanopatterning techniques. While it has been successfully implemented in traditional microelectronic processes, selective nucleation of ALD on 2D materials has so far remained an unsolved challenge. In this article, a precise control of the selective deposition of ZnO on graphene at low temperatures (<250 °C) is demonstrated. Maskless femtosecond laser writing is used to locally activate predefined surface areas (down to 300 nm) by functionalizing graphene to achieve excellent ALD selectivity (up to 100%) in these regions for 6-nm-thick ZnO films. The intrinsic conductive properties of graphene can be restored by thermal annealing at low temperature (300 °C) without destroying the deposited ZnO patterns. As the graphene layer can be transferred onto other material surfaces, the present patterning technique opens new attractive ways for various applications in which the functionalized graphene is utilized as a template layer for selective deposition of desired materials.peerReviewe

Coupled thermal analysis of carbon layers deposited on alumina nanofibres

Catalyst-free chemical vapor deposition is used to form thin (1–2 nm) carbon layers on the surface of alumina nanofibers resulting in carbon-alumina nanocomposites. Thermal analysis, X-ray fluorescent microanalysis, Raman spectroscopy, and electrical resistance measurements of these composites show that increasing of synthesis time not only increases the amount of carbon on alumina surface, but also the ordering and density of the carbon layers. Nitrogen adsorption data reveal the decrease of total pore volume with increasing the synthesis time. The obtained composite material could be employed for the preparation of ion-selective membranes with switchable ion transport, electroconductive ceramics, and electrochemical sensors

Thermoelectrically Driven Photocurrent Generation in Femtosecond Laser Patterned Graphene Junctions

Single and few-layer graphene photodetectors have attracted much attention in the past few years. Pristine graphene shows a very weak response to visible light; hence, fabrication of complex graphene-based detectors is a challenging task. In this work, we utilize the ultrafast laser functionalization of single-layer CVD graphene for highly desirable maskless fabrication of micro- and nanoscale devices. We investigate the optoelectronic response of pristine and functionalized devices under femtosecond and continuous wave lasers irradiation. We demonstrate that the photocurrent generation in p–p+ junctions formed in single-layer graphene is related to the photothermoelectric effect. The photoresponsivity of our laser patterned single-layer graphene junctions is shown to be as high as 100 mA/W with noise equivalent power less than 6 kW/cm2. These results open a path to a low-cost maskless technology for fabrication of graphene-based optoelectronic devices with tunable properties for spectroscopy, signal processing, and other applications

Quality of life and adherence to therapy in patients with chronic heart failure who were remotely monitored by chatbot compared to the standard follow-up group for 3 months

BACKGROUND: Chronic heart failure (CHF) is one of the leading causes of death. Telemedicine and remote monitoring (RM) are a way to increase life expectancy and quality of life in patients with CHF. Methods based on messengers familiar to patients promote adherence and do not require additional training. AIM: To compare quality of life and adherence to therapy in patients with CHF who were on RM using a chatbot compared to the standard follow-up (SFU) group for 3 months. METHODS: Patients with CHF on optimal drug therapy discharged from the hospital were included in the study. Comparison groups were formed according to the method of observation, particularly, RM and SFU. A chatbot was set up for patients in the RM group. Monitoring was done using a seven-question survey sent daily. The signs of decompensation (red flags [RF]) were increased edema, dyspnea, body weight 2 kg per week, and changes in individual parameters of heart rate and blood pressure. If a RF was detected, telephone contact was made, and the therapy was corrected if necessary. Quality of life was assessed according to the Minnesota Quality of Life Questionnaire for patients with CHF (highest, 0 points; lowest, 105 points), and adherence was assessed using the Adherence Scale of the National Society for Evidence-based Pharmacotherapy. RESULTS: A total of 60 patients were included in the study; 37 patients completed a 3-month follow-up. The RM group (n=17, 13 men, 76.5%; median age 61 [51; 62]) and comparison group (n=20, 14 men, 70%; mean age 64.98.9) were comparable according to the functional class (New York Heart Association), but differed in ejection fraction (42.813% versus 53.210.4% [p 0.05]). Adherence to the chat-bot was 67.2%. Adherence to therapy was not significantly different between the RM and SFU groups accounting for (17 [100%]) and (18 [90%], respectively, (p=0.62). In the RM group, RF was detected in 7 (41%) patients. Only one patient required correction of therapy. Patients in the RM group required no referral to a medical facility, whereas 2 patients in the SFU group required medical care. Quality of life was statistically significantly higher in the RM group, reaching 28.713.9 points compared to 37.717.9 points in the SFU group (p=0.04). CONCLUSIONS: After 3 months, patients in the RM group were committed to the chatbot, with adherence to therapy comparable to the SFU group. Quality of life was statistically significantly higher in the RM group. Patients in the RM group did not go to medical facilities, in contrast to the SFU group. The limitations of the study were the small sample size and short follow-up period. The results require further research to obtain additional data

Differential Bio-Optoelectronic Gating of Semiconducting Carbon Nanotubes by Varying the Covalent Attachment Residue of a Green Fluorescent Protein

Publisher Copyright: © 2022 The Authors. Advanced Functional Materials published by Wiley-VCH GmbHIntegrating photoactive proteins with synthetic nanomaterials holds great promise in developing optoelectronic devices whereby light, captured by a antenna protein, is converted to a modulated electrical response. The protein–nanomaterial interface is critical to defining optoelectronic properties; successful integration of bionanohybrids requires control over protein attachment site and a detailed understanding of its impact on device performance. Here, the first single-walled carbon nanotube (SWCNT) bio-optoelectronic transistor enabled by the site-specific direct interfacing with a green fluorescent protein (GFP) via genetically encoded phenyl azide photochemistry is reported. The electrical behavior of individual semiconducting SWCNTs depends on the protein residue coupling site and provides the basis to design eco-friendly phototransistors and optoelectronic memory. Attachment at one GFP residue proximal to the chromophore produces a wavelength-specific phototransistor. The bio-transistor can be switchedoff in less than 38 s with responsivity up to 7 × 103 A W−1 at 470 nm. Attachment via a second residue distal to the chromophore generates optoelectronic memory that show rapid and reproducible conductivity switching with up to 15-fold modulation that is restored on the application of a gate voltage. Therefore, photoactive proteins, especially GFP, can be realized as a key material for novel single-molecule electronic and photonic devices.Peer reviewe

Exploring the performance of a functionalized CNT-based sensor array for breathomics through clustering and classification algorithms: from gas sensing of selective biomarkers to discrimination of chronic obstructive pulmonary disease

Funding Information: Breath samples were collected (aer signed consent) from 11 volunteers aged 22–88 years. Among them, 7 volunteers suffer from COPD, while 4 were healthy control volunteers. All volunteers were recruited within a research project funded by the UniversitàCattolica del Sacro Cuore in the frame of the 2016–2018 D 3.2 Strategic Program “Anapnoi”. For each volunteer, several samples were collected on different days. An overall number of 52 samples were analysed. Subject characteristics including age, gender, COPD category as well as the number of tests carried out for each subject are shown in Table S1 (in the ESI†). Breath sampling was carried out in a disposable bag (volume = 0.6 liters), containing the sensor array, and inated by breath through a disposable plastic straw. This procedure took around 10–15 seconds until the bag was fully inated. We did not record signicant differences among volunteers during the bag ination phase, likely due to the reduced volume to ll and to the lack ofany lter along the collection pipeline, which could hinder the bag ination step. The overall sensor exposure time inside the bag was set to 3 minutes, to let all sensors fully interact with the breath sample. Funding Information: G. D., S. P., M. C., S. F., P. M., and L. S. acknowledge funding by the UniversitàCattolica del Sacro Cuore in the frame of the 2016–2018 D 3.2 Strategic Program “Anapnoi”. L. S. and S. P. acknowledge funding by the Italian Ministry of Education, Universities, and Research (MIUR) through the PRIN 2017-N. 2017NYPHN8 (MADAM) program. F. S. F. and A. G. N. acknowledge Russian Foundation of Basic Research project no. 20-03-00804. I. I. B. acknowledges funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 739570 (ANTARES). Publisher Copyright: © The Royal Society of Chemistry.An array of carbon nanotube (CNT)-based sensors was produced for sensing selective biomarkers and evaluating breathomics applications with the aid of clustering and classification algorithms. We assessed the sensor array performance in identifying target volatiles and we explored the combination of various classification algorithms to analyse the results obtained from a limited dataset of exhaled breath samples. The sensor array was exposed to ammonia (NH3), nitrogen dioxide (NO2), hydrogen sulphide (H2S), and benzene (C6H6). Among them, ammonia (NH3) and nitrogen dioxide (NO2) are known biomarkers of chronic obstructive pulmonary disease (COPD). Calibration curves for individual sensors in the array were obtained following exposure to the four target molecules. A remarkable response to ammonia (NH3) and nitrogen dioxide (NO2), according to benchmarking with available data in the literature, was observed. Sensor array responses were analyzed through principal component analysis (PCA), thus assessing the arrayselectivity and its capability to discriminate the four different target volatile molecules. The sensor array was then exposed to exhaled breath samples from patients affected by COPD and healthy control volunteers. A combination of PCA, supported vector machine (SVM), and linear discrimination analysis (LDA) shows that the sensor array can be trained to accurately discriminate healthy from COPD subjects, in spite of the limited dataset.Peer reviewe

Development of a Sensing Array for Human Breath Analysis Based on SWCNT Layers Functionalized with Semiconductor Organic Molecules

A sensor array based on heterojunctions between semiconducting organic layers and single walled carbon nanotube (SWCNT) films is produced to explore applications in breathomics, the molecular analysis of exhaled breath. The array is exposed to gas/volatiles relevant to specific diseases (ammonia, ethanol, acetone, 2-propanol, sodium hypochlorite, benzene, hydrogen sulfide, and nitrogen dioxide). Then, to evaluate its capability to operate with real relevant biological samples the array is exposed to human breath exhaled from healthy subjects. Finally, to provide a proof of concept of its diagnostic potential, the array is exposed to exhaled breath samples collected from subjects with chronic obstructive pulmonary disease (COPD), an airway chronic inflammatory disease not yet investigated with CNT-based sensor arrays, and breathprints are compared with those obtained from of healthy subjects. Principal component analysis shows that the sensor array is able to detect various target gas/volatiles with a clear fingerprint on a 2D subspace, is suitable for breath profiling in exhaled human breath, and is able to distinguish subjects with COPD from healthy subjects based on their breathprints. This classification ability is further improved by selecting the most responsive sensors to nitrogen dioxide, a potential biomarker of COPD.Peer reviewe